Never heard of them either. But to me, all HDMI cables are the same (more or less) in terms of quality, so right now, it's really down to size / length vs price? Normal HDMI cables tend to be thicker and bulkier (normally not an issue when I chuck them behind the TV). I find the Apple HDMI cable thinner and so easier to coil and tuck away.
RedMere is a company that created cables which have an active Integrated Circuit (IC) chip embedded in the connector that helps manage the signal allowing manufactures to make thinner cables using less copper that perform like standard passive cables.